Skewed Non-Fermi Liquids and the Seebeck Effect

Georges, Antoine; Mravlje, Jernej

doi:10.48550/arxiv.2102.13224

Cited by 4 publications

(8 citation statements)

References 50 publications

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“…As recently shown in Ref. [43], such a particlehole asymmetry in skewed non-Fermi liquids leads to an unconventional Seebeck effect at low-T . Whether this asymmetry persists down to zero temperature at the QCP (i.e.…”

supporting

confidence: 61%

“…Furthermore, we demonstrate ω/T scaling of both the local spin dynamics, which is found to be of SYK type as in the undoped case [27], and of the single-particle properties such as the frequency-dependent scattering rate. In the accessible range of temperature, the latter is found to display an intrinsic particle-hole asymmetry ('skewed' non-Fermi liquid [43]). We establish the phase diagram displayed in Fig.…”

mentioning

confidence: 99%

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Planckian Metal at a Doping-Induced Quantum Critical Point

Dumitrescu,

Wentzell,

Georges

et al. 2021

Preprint

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We numerically study a model of interacting spin-1/2 electrons with random exchange coupling on a fully connected lattice. This model hosts a quantum critical point separating two distinct metallic phases as a function of doping: a Fermi liquid with a large Fermi surface volume and a low-doping phase with local moments ordering into a spin-glass. We show that this quantum critical point has non-Fermi liquid properties characterized by T -linear Planckian behaviour, ω/T scaling and slow spin dynamics of the Sachdev-Ye-Kitaev (SYK) type. The ω/T scaling function associated with the electronic self-energy is found to have an intrinsic particle-hole asymmetry, a hallmark of a 'skewed' non Fermi liquid.

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supporting

confidence: 61%

mentioning

confidence: 99%

Planckian Metal at a Doping-Induced Quantum Critical Point

Dumitrescu,

Wentzell,

Georges

et al. 2021

Preprint

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“…It is interesting to note that, for a nFL with ImΣ ∝ T ν and ν < 1, the latter always displays Planckian behavior ∝ T , independently of the value of the exponent ν since Z(T, ω = 0) vanishes as Z(T ) ∝ T 1−ν . Indeed, the real part of the self-energy is related to the imaginary part by ReΣ(ω) = − dω ImΣ(ω )/π ω−ω , from which it follows for ν < 1 that ReΣ(ω) = T ν f (ω/T ) and hence 1/Z = 1 − ∂ ω ReΣ = 1 − T ν−1 f (ω/T ); see (Georges and Mravlje, 2021) for details.…”

Section: E Transport In Random Exchange T-u -J Modelsmentioning

confidence: 99%

“…(5.25), and hence offers a possible probe of the residual T = 0 entropy. Recently, (Georges and Mravlje, 2021) emphasized that the intrinsic particle-hole asymmetry of the ω/T scaling function in Eq. (7.11), characteristic of 'skewed' Planckian (or sub-Planckian) metals, has remarkable consequences for the sign and Tdependence of the thermopower down to low-T , even in the presence of additional elastic scattering.…”

Section: E Transport In Random Exchange T-u -J Modelsmentioning

confidence: 99%

“…In this respect, recent nuclear magnetic resonance and ultrasound measurements have revealed that, remarkably, the spin-glass phase extends up to p = p * for La 2−x Sr x CuO 4 subject to a high magnetic field (Frachet et al, 2020). The critical theory of the random exchange models is not particle-hole symmetric, and the possible relevance of the intrinsic particle-hole asymmetry of the ω/T scaling function associated with the scattering rate has been recently emphasized for the interpretation of Seebeck measurements on the cuprates (Georges and Mravlje, 2021;Gourgout et al, 2021).…”

Section: G Experimental Relevancementioning

confidence: 99%

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Sachdev-Ye-Kitaev Models and Beyond: A Window into Non-Fermi Liquids

Chowdhury,

Georges,

Parcollet

et al. 2021

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We present a review of the Sachdev-Ye-Kitaev (SYK) model of compressible quantum many-body systems without quasiparticle excitations, and its connections to various theoretical studies of non-Fermi liquids in condensed matter physics. The review is placed in the context of numerous experimental observations on correlated electron materials. Strong correlations in metals are often associated with their proximity to a Mott transition to an insulator created by the local Coulomb repulsion between the electrons. We explore the phase diagrams of a number of models of such local electronic correlation, employing a dynamical mean field theory in the presence of random spin exchange interactions. Numerical analyses and analytical solutions, using renormalization group methods and expansions in large spin degeneracy, lead to critical regions which display SYK physics. The models studied include the single-band Hubbard model, the t-J model and the two-band Kondo-Heisenberg model in the presence of random spin exchange interactions. We also examine non-Fermi liquids obtained by considering each SYK model with random four-fermion interactions to be a multi-orbital atom, with the SYK-atoms arranged in an infinite lattice. We connect to theories of sharp Fermi surfaces without any low-energy quasiparticles in the absence of spatial disorder, obtained by coupling a Fermi liquid to a gapless boson; a systematic large N theory of such a critical Fermi surface, with SYK characteristics, is obtained by averaging over an ensemble

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Thermopower across the phase diagram of the cuprate La1.6−xNd0.4SrxCuO4 : Signatures of the pseudogap and charge density wave

et al. 2021

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The Seebeck coefficient (thermopower) S of the cuprate superconductor La 1.6−x Nd 0.4 Sr x CuO 4 was measured across its doping phase diagram (from p = 0.12 to p = 0.25), at various temperatures down to T 2 K, in the normal state accessed by suppressing superconductivity with a magnetic field up to H = 37.5 T. The magnitude of S/T in the T = 0 limit is found to suddenly increase, by a factor 5, when the doping is reduced below p = 0.23, the critical doping for the onset of the pseudogap phase. This confirms that the pseudogap phase causes a large reduction of the carrier density n, consistent with a drop from n = 1 + p above p to n = p below p , as previously inferred from measurements of the Hall coefficient, resistivity, and thermal conductivity. When the doping is reduced below p = 0.19, a qualitative change is observed whereby S/T decreases as T → 0, eventually to reach negative values at T = 0. In prior work on other cuprates, negative values of S/T at T → 0 were shown to result from a reconstruction of the Fermi surface caused by charge density wave (CDW) order. We therefore identify p CDW 0.19 as the critical doping beyond which there is no CDW-induced Fermi surface reconstruction. The fact that p CDW is well separated from p reveals that there is a doping range below p where the transport signatures of the pseudogap phase are unaffected by CDW correlations, as previously found in YBa 2 Cu 3 O y and La 2−x Sr x CuO 4 .

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Skewed Non-Fermi Liquids and the Seebeck Effect

Cited by 4 publications

References 50 publications

Planckian Metal at a Doping-Induced Quantum Critical Point

Planckian Metal at a Doping-Induced Quantum Critical Point

Sachdev-Ye-Kitaev Models and Beyond: A Window into Non-Fermi Liquids

Thermopower across the phase diagram of the cuprate La1.6−xNd0.4SrxCuO4 : Signatures of the pseudogap and charge density wave

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